Process of separating and recovering iron and zinc from sulphide ores



Sept. 4, 1923. 1,466,793

F. A. EUSTIS ET AL.

- PROCESS OF SEPARATING AND RECOVERING IRON AND ZINC FROM SULPHII DE ORES Filed Sent. 29 1922 ZimaQone 4 7 4 /77 ZZeZroZysz'sZ?) sulphide iron are a l Coni'cvniw 2 291931;

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' ,FREDERIC A. EUSTIS, OF MILTON, AND DONALD BELCHER, OF BOSTONQ MASSACHU- SETTS, ASSIGNORS F ONE-HALF TO SAID EUSTIS A1\ T D ONE-HALF TO CHARLES PAGE PERIN, OF NEW YORK, N. Y.

rnoonss or SEPARA'IING AND inncovnnme IRON AND ZINC FROM scnrninn oREs.

Application filed September 29, 1922. Serial No. 591,270.

To all whom it may concern: Be it known that we, FREDEBIC A. EUSTIS and DONALD BELCHER, citizens of the United States of America, and residents of Milton 5 and Boston, respectively, in the countiesof Norfolk and Suffolk, and State of Massachusetts, have inventednew and useful Im pro-vements' in Processes of Separating and Recovering Iron and Zinc from Sulphide Ores, of which the" followingis a specification.

There aremany ores which carry a large percentage of iron'sulphide and relatively small quantities of copper, gold and silver, which often occur together, and there are other iron sulphides which carry as im-' "sometimes cadmium. I Such ores frequently include important quantities of zinc.-

portant minor metalsrnickel, cobalt and.

tion. Serial No. .-566, 581,' filed June 7-, 1922,.

(of, which this application is a continuation in part) we havefdescrib'ed a process having the advantages 'ofthe process of our said Patent No. 1,412,174 for treating the abovementioned class of ores containing associated metals," and resulting in recovering not only the iron and the sulphur, but also the other as associated metals.

mixed sulphide iron ores carrying the asso ciated metals by leaching the material with ferric 'chloride'to dissolve the iron and a part at least of the associated metals, removing the associated metals soluble by this step by selective precipitation, and. electrolyzmg the iron solution, the anode liquor being returned to the leaching tank. Unless special steps are taken,the zinccontent tends to buildup in thecirculated solution.

' In respect to recovering the zinc, our said application Serial No. 566,581 described alternative procedures including electrodeposition of zinc (when the solution had built up to a sufiicient concentration) at the cathode along with the iron, and subsequent heating to drive ofi the zinc by-volatilization, but elected to claim species ofthe process in'which the zinc, if any, was precipitated from trolysis. k The present: invention relates to the recovery and separation of zinc and iron, or similarly related metals, by electrolysis from mixed ores, such as sulphides of zinc and lron, and apparatus therefor."

Such mixed sulphides are very common in nature. andin many ores, which may be the solution prior to electreated to advantage by the process described in our said application Serial No. 566,581, zinc is found in such quantities and under such conditions that it can not-be .commcrcially recovered under processes at present known. The present invention makes pos- 'sible the recovery of zinc at profit from such ores, with simultaneous recovery of pure ,"iron.

I In Letters Patenthf the United States No. 1,412,174, irantedto us and others April The invention will best be understood by reference to a typical recommended procedure illustrated in the accompanying drawing, in which the figure is a diagram explanatory of the preferred steps of the,

process and showin certain recommended types of apparatus or practising certain of said steps. r I

Referring to the drawing, the process may be carried out as follows:

Y The sulphide ores containing zinc and iron and other metals if present, will ,be first finely ground. If much of the iron is present as. pyrites, the. ores will then be heated as described in our said Patent No. The process in general, according to our, In Order 2 atom of said application, comprises treating the" Sulphur from the pyrite. The material will then be fed into the solution tank B. In this tank the iron. zinc and such other metals as copper, nickel, cobalt and cadmium. if.

present, will be taken into solution and at the'same time the solution will be chemically reduced. A suitable solvent is, for example,

av mixture of,ferric chloride and ferrous chloride, containing 72 grams of iron per, liter of ferric chloride and 72 grams of iron per liter of ferrous chloride, with or withresidue and without the addition of acid or other substance:

The reduced ferrous liquor containing the iron and-other associated metals iii solution containing the is then passed to the'til ter Q, where thciusoluble materials including silica, pre'c1pitated sulphur and any other materials such as gold and silver that have not been dissolved, will be collected as a filter cake from which the sulphur, gold and silver may be recovered by known methods. The clear solution of ferrous iron bearing also. the zinc, copper and other associatedmetals, if present, will then be delivered into the cementation tank E containing: scrap or other metallic iron which preci itates the copper in cement copper, and so. largely precipitates any gold or s lver taken into the solution. be other associated metals, if present may be treated as described n our said application Serial No. 566,581, selectively to precipitate them from the solution.

From time cementation tank E the clear solution of ferrous chloride,-carr \'ing also the zinc, is pumped through tank containing limestone to the cathode compartment of the electrolysis cell A. The limestone in tank D is preferred to be employed as a safequa rd to neutralize any remaining traces of ferric chloride, and to insure that the solution shall be neutral zed and enter the electrolysis cell in a ferrous state.

If desired the solution, before reaching.

the electrolysis cell It, may be purifi from arsenic, antimony or other impurities by selective precipitation or combination, as described in our said application, Serial No.

If 'tis not suficient-ly hot, the solution is heated to approximate-1v the boiling oint.

In the electrolysis cel A iron and z nc is deposited on the cathode. and the solution is regenerated, a part of the ferrous chloride becoming ferricchloride. The anode liquor ferric chloride is then delivered to the solution tank Bto he used over again, thus completing the cycle.

Any suitable form of electrolysis tank,

such as that described in our Patent No. 1,412,17 or that described in our said application Serial No. 566,581, may be used. Since according to the present invention the metal is to be remclted, a simple form of electrolysis tank without provision for homogeneous deposit is preferred. The combined metals, iron and zinc, as deposited. therefore be brittle, which makes it possible to remove them from fixed, solid or flexible cathodes with great ease.

The deposited mixed metal at the cathodes is now from time to time or continuous- 1y stripped from the, cathodes, broken up at 20, dried at and delivered to apparatus for practising the further steps. raising the. temperature of the metal in successive stages above the volatilization-point of zinc. and above the melting-pointof iron in a reducmg atmosphere; conducting away the zinc ing a tern contain much hydrogen and will.

escapes condensing tl iese vaors in a, re

enstin the, collected molten zinc in ingots; and drawing oil and casting the molten iron residue in' suitable ingots (or puddling for a ductile massif so erefrred).

The drawing indicates thepreterred apparatus. Delivery of the broken cathode deposit may be into a hopper arranged to deliver to a feed screw 31 in a pipe 32, screw 31 and the material acting as a. seal for the enclosed electric furnace 33 havin' a. vapor duct 3% and a tap-gate 35 for t e bolten iron, a pool of r. rich is maintained in the bottom of the furnace. The furnace may be of any desired type capable of maintainerature above tha of molten iron in a chain er inaccessible to oxygen or other combining elements. The pug: oses of this furnace include distillatio out chemical reactions into a homogeneous liquid or tax than the zinc.

Duet 3-t deli e1's into a condenser P P due-mg atmosphere;

melting the llOIl mass Without othcrablyf maintained by insulation 37 at a temperature above the melting point of z nc.

The molten zinc from condeuserBG may be tapped ofi through gate 38.

In operation, the feed-.SQW 31 delivers new material into the pool of molten metal in furnace 33 at a rate not too great to counterbalance the heating effect of the charge resistance electrical heating indicated by the electrodes 30 and circuit 4:1, or of whatever temperatursmaintaining heating device, operating without chemical reactions on the charge and the contained vapors, may )e of t e zinc rit-hsubstituted tor said electrodes and circuit.

Each acce s on ofu, portion of the cathode r t' n t rais d by he mo P in thefurnace to a temperature melting and then driving ed in vapor the zinc, and then melting the iron.

We claim:

L- lhe art of treating ores containing iron and zinc comprising subjecting the ores to solution and the solution to electrolysis for the recovery of a cathode depositof mixed iron and zinc, and subjecting thus-aid deposit to temperatures above the vqlatilization i point otz mc, whereby to drive qti the sine by olat hzation and recover pure iron.

2. The art of treating ores containing iron and nine comprising subjecting. the ores to solution andthe solution to electrolysis tor the recovery of a cathode dep t of mixed iron and zinc, and subjecting t e said deposit to temperatures above the vo atilization point of zinc in a reducing atmosphere,and removing and condensing the vapor to reco er metallic zinc.

3. The art of treating ores containing iron and comprising subjecting the ores to solution and the solution to electrolysis for the recovery of a cathode deposit at it to temperatures above the melting reeeye and subjecting the said depospoint to drive off the zinc by recover pure iron in a iron and zinc,

of iron, whereby volatilization and molten state.

4. The art of recovering zinc from iron sulphide ores comprising forming an elec trolyte containing iron and salts of zinc, depositing the said metals as a cathode deposit by electrolysis, subjecting the cathode deposit to distillation at a temperature in excess of the vaporization temperature of zinc and condensing the vapor.

5. The art of recovering zinc from iron sulphide ores comprisin forming an electrolyte containing iron in the 'ferrousstate and salts of'zinc, depositing the said metals as a cathode deposit by-electrolysis, subjecting the cathode deposit to distillation at a temperature in excess of the vaporization temperature of zinc in a reducing atmosphere and condensing the vapor.

6. The art of recovering zinc and iron from sulphide ores comprising subjecting suitably prepared ore to leaching with an iron solution, causin .the solution to be selectively precipitate in respect to other of the contained metals than iron and zinc, subjecting the solution-to electrolysis to recover a cathode deposit of mixed iron and zinc, and subjecting the cathode deposit so obtained to fractional distillation to separate the pure iron and pure zinc.

7. The art of recovering zinc and iron from sulphide ores containing other valuable metals comprising subjecting suitably prepared ore to leaching with an iron solution, removing solids containing some of said other metals, causing the remainin solution to be selectively precipitated in respect to other of the contained metals than iron and zinc, subjecting the solution to electrolysis to recover a cathode deposit of mixed iron and zinc, and subjecting the cathode deposit so obtained to fractional distillation in a reducin atmosphere to separate'the pure iron an pure zinc.

8. The art of recoverin zinc and iron comprising subjecting suita 1y prepared'ore to repeated leaching with an iron solution, causing the solution to be tained metals than iron and zinc, subjecting and condensing the vapor in the selectively pre- 'cipitated in respect to other of the contration of the zinc in solution, and sub'ectingthe cathode deposit so obtained to ractional distillation to separate the pure iron and pure zinc.

9. The art of recoveringthe pure metalsfrom sulphide, iron ores containing zinc comprisin roasting the-ores to lower the content 0 combined sulphur, subjecting the treated ore to repeated leaching with a solutioncontaining iron in the ferric state and without free acid, subjecting the solution reduced thereby to the ferrous state to steps for the removal of solids and selective preeipitation of metals other than iron and zinc, simultaneously regenerating the ferric 'solution and depositing iron and zinc as a cathode deposit in an electrolytic cell; returning the regenerated solution to dissolve more ore; and treating the cathode deposit by progressively increasing its temperature beyond the melting point of iron, collecting absence of whereby to recover zinc combining elements,

pure iron as a molten as a distillate, and metallic residue. v

10. That step in the art of obtaining ure metallic iron and pure metallic zinc rom sulphide ores contarningiron and zinc comprising the formation of a.mixed friablecathode deposit of iron and zinc by electrolysis from a solution containing the salts of iron and zinc.

11. Those steps in the art of obtaining g pure metallic iron and pure metallic zinc from'sulphide ores containin v iron and zinc comprising the formation 0? a mixed iriable cathode deposit of iron and "inc by electrolysis from a solution containing the salts of iron and zinc, breaking and drying 'the cathode deposit, and su jecting it to fractional distillation.

Signed by us at Boston, Massachusetts, and at New York, New York, this 25th day of September, and this 26th day of Sep: tember, 1922, respectively.

FREDERIC A. EUSTIS. DON ALI) BELCHER. 

